Computer Output

by ronaldo7, Apr 23, 2007

About computer output device and how its works.

Data that has been processed into a useful form,
called information.
Output device is any hardware component that can convey
information to user.

Output device that visually conveys information on display device sometimes
called soft copy.
Monitor houses display device as separate peripheral

Sharpness and clarity of image
Higher resolution makes image sharper, displays more text on screen, makes some elements smaller
Refresh rate is speed at which monitor redraws images on screen

Video card (also called a graphics card) converts digital output from computer into analog video signal

Step 1: The processor sends digital video data to the video card.
Step 2: The video card's digital-to-analog converter (DAC) converts the digital video data to an analog signal.
Step 3: The analog signal is sent through a cable to the CRT monitor.
Step 4: The CRT monitor separates the analog signal into red, green, and blue signals.
Step 5: Electron guns fire the three color signals to the front of the CRT.
Step 6: An image is displayed on the screen when the electrons hit phosphor dots on the
back of the screen.

Step 1. Panel of fluorescent tubes emits light waves through polarizing glass filter, which guides light toward layer of liquid crystal cells.
Step 2. As light passes through liquid crystal, electrical charge causes some of the cells to twist, making light waves bend as they pass through color filter.
Step 3. When light reaches second polarizing glass filter, light is allowed to pass through any cells that line up at the first polarizing glass filter. Absence and presence of colored light cause image to display on the screen.

Impact printer that produces printed images when tiny wire pins strike ribbon
Impact printer forms characters by striking mechanism against inked ribbon that contacts paper

High-speed, high-quality nonimpact printer
Prints text and graphics in very high-quality resolution, ranging from 600 to 2,400 dpi
Typically costs more than ink-jet printer, but is much faster

Step 1. After user sends an instruction to print a document, drum rotates as gears and rollers feed sheet of paper into printer.
Step 2. Rotating mirror deflects low-powered laser beam across surface of drum.
Step 3. Laser beam creates a charge that causes toner to stick to drum.
Step 4. As drum continues to rotate and press against paper, toner transfers from drum to paper.

Step 5. Set of rollers uses heat and pressure to permanently fuse toner to paper.

Generates images by pushing electrically heated pins against heat-sensitive paper
Dye-sublimation printer, (also called a digital photo printer) uses heat to transfer dye to specially coated paper